Data decoding device, data decoding method, semiconductor integrated circuit and data decoding system

ABSTRACT

A data decoding device for decoding a compressed and coded data includes: an inverse multiplexing part configured to separate compressed and coded data into a plurality of unit data, then separated, from the unit data, more than one type of a data pack, and adding a tag such that the data pack can be identified as separating from the same unit data; and a decoding part configured to monitor the tag, while carrying out decoding of the data pack separated from the same unit data for each unit of the unit data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims priority of Japanese PatentApplication No. 2004-270071, filed in Sep. 16, 2004, the contents beingincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data decoding device, a data decodingmethod, a semiconductor integrated circuit and a data decoding systemfor decoding data compressed and coded according to a DVD standard.

2. Description of the Related Art

Recently, a DVD attracts an attention as a storage medium. In such aDVD, a bit stream compressed and coded according to a video standard isrecorded. The video stream compressed and coded according to the videostandard is called a video object (VOB).

FIG. 1 shows a data structure of one example of the VOB. VOB 1 can beseparated into decoding units called cells 2. Further, the cell 2 can beseparated into minimum units called video object units (VOBU) 3. TheVOBU 3 always starts from a single navy pack (Nv_pck), and can include,subsequent to the navy pack, video packs (V_pct), audio pack (A_pack)and sub-picture packs (Sp_pck), as shown.

The navy pack is a pack for controlling, including reproductioninformation (PCI) and address information (DSI) on a disk for the videopacks, audio packs and sub-picture packs. Each VOBU 3 absolutelyincludes one navy pack. The video packs, audio packs and sub-picturepacks should not be absolutely included in each VOBU 3.

The term ‘pack’ means a collection of data having a data length of 2048bytes, and includes a pack header and packets. Japanese Laid-open PatentApplication No. 11-162119 discloses a method for reproducing VOBaccording to a DVD video standard.

FIG. 2 shows a configuration diagram of one example of a data decodingdevice for decoding VOB. Ordinarily, the data decoding device decodesVOB for each VOBU unit. The data decoding device shown in FIG. 2generally includes a hardware 100 and a software 200. First, descriptionis made for the hardware 100.

The VOB read out from a DVD disk 10 is stored in a track buffer(Trk_buff) 101 of the hardware 100. At this time, the VOB is managed foreach VOBU unit with a separation therebetween. Subsequent to the trackbuffer 101, a demux (DEMUX) 102 for separating the VOBU into respectivepacks of the above-mentioned four types, i.e., the navy pack, videopacks, audio packs and sub-picture packs is connected.

Subsequent to the demux 102, a video buffer (Video_buff) 103, an audiobuffer (Audio_buff) 104, a sub-picture buffer (Sp_buff) 105 and a navybuffer (Nv_buff) 106 for storing the respective packs are connected.

Bit streams read out from the video buffer 103, the audio buffer 104 andthe sub-picture buffer 105 are decompressed by a video decoder(Video_Decoder) 107, an audio decoder (Audio Decoder) 108 and asub-picture decoder (Sp_Decoder) 109, respectively, thus become a formof video, audio and subtitle, and are output from the hardware 100.

Next, description is made for the software 200. A current manger 202reads out the navy pack from the navy buffer 106, and stores it in anavy spool (Nv_spool) 203. A reproduction engine 204 reads the navy packfrom the navy spool 203, and carries out control for actual datareproduction. A basic configuration of the software 200 includes thecurrent managing part 202, the navy spool 203 and the reproductionengine 204.

The reproduction engine 204 extracts the PCI from the navy pack thusread out from the navy spool 203, and transmits it to a STC alarmregistration managing part 206. The reproduction engine 204 transmitshighlight information (HLI) to the STC alarm registration managing part206 via a highlight information control part (HLI control part) 205.

VOBU_S_PTM included in the PCI is transmitted to the STC alarmregistration managing part 206 from the current managing part 202.VOBU_E_PTM included in the PCI is transmitted to the STC alarmregistration managing part 206 from the reproduction engine 204.HL_S_PTM, HL_E_PTM and BTN_SL_E_PTM included in the HLI are transmittedto the STC alarm registration managing part 206 from the reproductionengine 204 via the HLI control part 205.

The STC alarm registration managing part 206 registers the receiveddata, i.e., time information included in the PCI, that is, VOBU_S_PTM,VOBU_E_PTM, HL_S_PTM, HL_E_PTM and BTN_SL_PTM in a system clock (STC)201 in the ascending order. The STC 201 starts time measurementsimultaneously upon a start of data reproduction, and, when a registeredtime has been reached, the STC 201 notifies the reproduction engine 204and the HLI control part 205 of an alarm.

FIGS. 3 and 4 are a flow chart showing one example of operation of thedata decoding device. Here, description is made paying attention to therespective buffers and the navy pack. In Step S1, it is determinedwhether or not the track buffer 101 has a free storage space.

When a free storage space exists (Yes in Step S1), a VBO request isissued in Step S2, and, in Step S3, VOB is transferred from the DVD disk10 to the track buffer 101. When there is no free storage space (No inStep S1), Step S4 is executed, and thus, issuance of the VOB request isstopped.

Then in Step S5, it is determined whether or not any one of the videobuffer 103, the audio buffer 104, the sub-picture buffer 105 and thenavy buffer 106 has no more free storage space.

When all of the above-mentioned four buffers still have free storagespaces (No in Step S6), Step S5 is executed in which VOBU is input tothe demux 102 from the track buffer 101. When any one of the fourbuffers has no more free storage space (Yes in Step S6), Step S7 iscarried out in which input of VOBU to the demux 102 is stopped. That is,when any one of the four buffers has no more free storage space, inputof VOBU is stopped also with respect to other buffers still having freestorage spaces.

Then, Step S8 is repeated until the navy packs are stored in the navybuffer 106 (No in Step S8). When the navy packs are stored in the navybuffer 106 (Yes in Step S8), the current managing part 202 is notifiedof a navy pack writing finish notification. In Step S9, the currentmanaging part 202 obtains the navy pack from the navy buffer 106 via ahost interface (Host I/F) part 110.

Then, in Step S10, the current managing part 202 stores the navy packthus obtained from the navy buffer 106, in the navy spool 203. As longas any free storage space exists in the navy spool 203 (No in Step S11),the current managing part 202 repeats the processing of Steps S8 throughS11, and stores the navy pack obtained from the navy buffer 106, in thenavy spool 203 repetitively.

When the navy spool 203 has no more free storage space (Yes in StepS11), the current managing part 202 executes Step S12, and thus,registers VOBU_S_PTM(0) in the STC alarm registration managing part 206in prior to other parameters. Then in Step S13, the reproduction engine204 obtains the first navy pack Nv_pck(0) from the navy spool 203.

In Step S14, the reproduction engine 204 extracts HLI from the navy packNv_pck(0), and transmits it to the HLI control part 205. In Step S15,the reproduction engine 204 registers VOBU_E_PTM(0) in the STC alarmregistration managing part 206.

In Step S16, the HLI control part 205 registers HL_S_PTM(0), HL_E_PTM(0)and BTN_SL_E_PTM(0) in the STC alarm registration managing part 206.

In the processing so far, reproduction preparation for the first navypack Nv_pck(0) is completed. The processing of Steps S12 through S16 iscalled ‘reproduction standby’. In Step S17, processing of Step S17 isrepeated until it is determined that reproduction is started (Yes inStep S17). When it is determined that reproduction is started (Yes inStep S17), decoding of the bit streams stored in the video buffer 103,the audio buffer 104 and the sub-picture buffer 105 is started. In StepS19, the STC 201 starts counting.

In Step S20, the current managing part 202 registers VOBU_S_PTM(1) inthe STC alarm registration managing part 206. In Step S21, processing ofStep S21 is repeated until a reproduction start time VOBU_S_PTM(1) forthe second navy pack Nv_pck(1) is reached (No in Step S21).

After that, a time has elapsed and thus, the reproduction start timeVOBU_S_PTM(1) for the second navy pack Nv_pck(1) has been reached, theSTC 201 executes Step S22, and thus, it notifies the reproduction engine204 and the HLI control part 205 of an alarm. In Step S23, thereproduction engine 204 then obtains the second navy pack Nv_pck(1) fromthe navy spool 203.

In Step S24, the reproduction engine 204 extracts HLI from the secondnavy pack Nv_pck(1) and transmits it to the HLI control part 205. InStep S25, the reproduction engine 204 registers VOBU_E_PTM(1) in the STCalarm registering managing part 206.

In Step S26, the HLI control part 205 registers HL_S_PTM(1), HL_E_PTM(1)and BTN_SL_E_PTM(1) in the STC alarm registration managing part 206. InStep S27, it is determined whether or not reproduction is stillcontinued. When it is determined that reproduction is continued (Yes inStep S27), the processing of Steps S20 through S26 is carried out forthe subsequent navy pack. That is, as a result of the processing ofSteps S20 through S27 is repeated, data reproduction from the DVD diskis carried out.

On the other hand, when it is determined that reproduction is no morecontinued (No in Step S27), decoding of the bit streams stored in thevideo buffer 103, audio buffer 104 and the sub-picture buffer 105 isstopped. Then in Step S29, the STC 201 stops counting, and holds thecurrent count value.

SUMMARY OF THE INVENTION

In the above-described data decoding device, a problem occurs when VOBUsuch as that shown in FIG. 5 is decoded. FIG. 5 shows a data structureof one example of VOBU. VOBU shown includes audio in two types, i.e., avoice of English and a voice of Japanese. In FIG. 5, the audio packcorresponding to the English voice is expressed as A_pck(E) while theaudio pack corresponding to the Japanese voice is expressed as A_pck(J).

Normally, in VOBU, the audio packs corresponding to the English voiceand the audio packs corresponding to the Japanese voice are multiplexedevenly. However, in VOBU shown in FIG. 5, the multiplexing has adeviation between the audio packs corresponding to the English voice andthe audio packs corresponding to the Japanese voice as shown.

For example, in FIG. 5, the audio packs corresponding to the Englishvoice are multiplexed in VOBU(n) through VOBU(n+5), while the audiopacks corresponding to the Japanese voice are multiplexed in VOBU(n+6).The video packs corresponding to a video are multiplexed in VOBU(n) andVOBU(n+1). On the other hand, no sub-picture packs corresponding tosubtitles are not multiplexed there.

With reference to FIGS. 6 and 7, description is made for a statetransition of the four buffers, i.e., the video buffer 103, the audiobuffer 104, the sub-picture buffer 105, the navy buffer 106, and thenavy spool 203 for a case where data reproduction is carried out fromVOBU shown in FIG. 5, and switching is made in a voice from English toJapanese in the above-described data decoding device. FIGS. 6 and 7 showstate transmission diagrams for these four buffers and the navy spool.

A state of FIG. 6, (A) is an initial state before a start of datareproduction. In this state, the four buffers and the navy spool 203 arefree as shown. The track buffer not shown in FIGS. 6 and 7 is also free.

Since the track buffer 101 is free in this state, a VOB request isissued, and transfer of VOB from the DVD disk 10 to the track buffer 101is started. After that, VOB thus stored in the track buffer 101 is inputto the demux for each VOB unit, is separated into the respective fourtypes of packs described above by the demux 102, and is stored in therespective relevant buffers.

In a state of FIG. 6, (B), the navy buffer 106 has no more free storagespace, input of VOBU to the demux 102 is stopped, and issuance of theVOB request is stopped. After that, the above-mentioned reproductionstandby processing is carried out.

In a state of FIG. 6, (C), reproduction processing is started, thereproduction engine 204 reads out the navy packs from the navy spool 203and consumes them. Further, the current managing part 202 reads out thenavy packs from the navy buffer 106, and consumes them. At this time,the audio packs A_pck(E) corresponding to the English voice are storedin the audio buffer 104, and as a result, an English voice is output. InFIGS. 6 and 7, the thus-consumed navy packs are crossed off by lines(-).

Then, it is assumed that a user gives an instruction to switch the voicelanguage. Upon issuance of this voice switching instruction, the datadecoding device flashes (deletes) the audio packs A_pck(E) currentlystored in the audio buffer 104. A state of FIG. 6, (D) is a state inwhich, the voice switching instruction is issued, and thus the audiopacks are flashed from the audio buffer 104. The video packs stored inthe video buffer 103 are consumed.

After that, waiting is carried out until the audio pack A_pck(J) isstored in the audio buffer 140, and then, data reproduction is startedagain after the audio pack A_pck(J) is stored in the audio buffer 104.However, as shown in FIG. 7, (E), storage of the audio pack A_pck(J) forthe audio buffer 104 is carried out after all the navy packs stored inthe navy buffer 106 are read out and flashed (deleted).

To read out all the navy packs from the navy buffer 106 means to consumeall the navy packs stored in the navy spool 203. The is, storage of theaudio pack A_pck(J) for the audio buffer 104 is started, as shown inFIG. 7, (F), after all the navy packs stored in the navy buffer 106 andthe navy spool 203 are consumed. A state of FIG. 7, (G) is a state inwhich storage of the audio packs A_pck(J) in the audio buffer 104 hasbeen completed.

A fact that no audio pack A_pck(J) is stored in the audio buffer 104means that no Japanese voice is output. Accordingly, in this datadecoding device in the related art, a voice interruption may continuefor a so long time upon voice switching, that it may be recognized by auser. A maximum time Tmax for which the voice interruption may continueupon voice switching may be expressed by the following formula (1):Tmax=(maximum reproduction time of VOBU)×(capacity of Nv_buff+capacityof Nv_spool)  (1)

For example, for a case where the maximum reproduction time of VOBU is0.5 seconds, and a capacity of each of the navy buffer 106 and the navyspool 203 is 16 packs, the maximum time Tmax of the voice interruptionupon voice switching is calculated as being 16 seconds.

A first reason why the voice interruption upon voice switching is thuslong is that the navy buffer 106 is made of a memory for whichoverwriting is not allowed. The navy buffer 106 is thus made of theoverwriting inhibited memory since the navy packs for control should notbe erased improperly. In fact, if the navy packs are erased or readingout thereof is failed in, PCI, DSI or such of the video packs, audiopacks and sub-picture packs separated from the same VOBU are lostaccordingly.

A second reason why the voice interruption upon voice switching is thuslong is that, as shown in FIG. 7, (E), even though all the video buffer103, the audio buffer 104 and the sub-picture buffer 105 become free,the navy packs corresponding thereto are still read out from the navybuffer 106 and are still consumed.

That is, although the video buffer 103, the audio buffer 104 and thesub-picture buffer 105 have no more video pack, no more audio pack andno more sub-picture pack, respectively, to be controlled, only the navypacks separated from the same VOBU are still consumed according to theregistered time, and thus, the voice interruption upon voice switchingbecomes longer.

In this case, the navy packs stored in the navy buffer 106 and the navyspool 203 have become no more necessary, and thus, may be immediatelyflashed. That is, the second reason why the voice interruption uponvoice switching becomes longer is caused by the first reason why thevoice interruption upon voice switching becomes longer, which firstreason is originally caused from the view point that the navy packsshould be protected as mentioned above.

In other words, the reason why the voice interruption upon voiceswitching becomes longer is that, since dependency relationship betweenthe navy packs and the other video packs, audio packs and sub-picturepacks is not maintained, the navy packs cannot be easily erased.

The present invention has been devised in consideration of theabove-mentioned point, and an object of the present invention is toprovide a data decoding device by which it is possible to shorten thevoice interruption or subtitle interruption upon voice switching orsubtitle switching.

According to the present invention, a data decoding device for decodinga compressed and coded data, includes: an inverse multiplexing partconfigured to separate compressed and coded data into a plurality ofunits of unit data, then further separate, from the unit data, more thanone type of a data pack, and adding a tag such that the data pack can beidentified as originating from the same unit data; and a decoding partconfigured to monitor the tag, while carrying out decoding of the datapack separated from the same unit data, for each unit of the unit data.The present invention may be embodied in a form of a data decodingmethod, a semiconductor integrated circuit, or a data decoding systemfor carrying out the above-mentioned data decoding device.

According to the present invention, the tab is added so that the datapacks separated from the same data unit can be identified. As a result,it is possible to easily identify the data packs of one or more typesseparated from the same unit data, and, it is possible to carry outdecoding of the data packs for each unit of the unit data whilemonitoring the tags.

As a result, upon voice switching or subtitle switching, it is possibleto easily identify the data packs separated from the same unit data, andthus, it is possible to rapidly erase the data packs of one or moretypes which originate from the same unit data and become no morenecessary. Thereby, it is possible to shorten the voice interruption orsubtitle interruption upon voice switching or subtitle switching.

Thus, according to the present invention, it is possible to provide adata decoding device by which it is possible to shorten the voiceinterruption or subtitle interruption even upon voice switching orsubtitle switching.

Other objects and further features of the present invention will becomemore apparent from the following detailed description when read inconjunction with the accompanying drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a data structure of one example of VOB;

FIG. 2 shows a configuration diagram of one example of a data decodingdevice for decoding VOB;

FIGS. 3 and 4 show a flow chart of operation of the data decodingdevice;

FIG. 5 shows a data structure of one example of VOBU;

FIGS. 6 and 7 show a state transition diagram of four buffers and a navyspool upon reproduction of VOBU;

FIG. 8 illustrates addition of a tag;

FIG. 9 shows a configuration diagram of a data decoding device fordecoding VOB in one embodiment of the present invention;

FIGS. 10 and 11 show a flow chart of operation of the data decodingdevice shown in FIG. 9;

FIGS. 12 and 13 show a state transition diagram of four buffers, a navyspool and a register upon reproduction of VOBU in the data decodingdevice shown in FIG. 9;

FIG. 14 shows a flow chart of one example of navy buffer flashprocessing according to the embodiment of the present invention; and

FIG. 15 shows a value of a tag added to each pack of four types ofpacks, and a value of a tag stored in a register and a pointer accordingto the embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Next, a best mode of carrying out the present invention is describedbased an embodiment described below with reference to figures. Althoughdescription is made paying attention to a voice interruption upon voiceswitching, the same manner can be applied also for a subtitleinterruption upon subtitle switching.

First, with reference to FIG. 8, addition of tags by which the navypacks, video packs, audio packs and sub-picture packs separated from thesame VOBU can be identified is described. FIG. 8 illustrates a tagadding manner.

VOBU 3 always starts from a single navy pack, and may include the videopacks, audio packs or sub-picture packs subsequent to the navy pack.Hereinafter, any one of the navy pack, video pack, audio pack andsub-picture pack may be simply referred to as a pack.

The navy pack 4 includes a pack header having four bytes and a PCI+DSIpacket. The video pack includes a pack header of 14 bytes and a videopacket. The audio pack includes a pack header of 14 bytes and an audiopacket. The sub-picture pack includes a pack header of 14 bytes and asub-picture packet.

According to the present invention, a tag is written in a pack startcode, located at the top of the pack header 5 and having four bytes. Thetag has the same value when the pack to which the tag is thus added isseparated from the same VOBU. For example, a value starting from 1 iswritten in the tag. Then, the value of the tag is incremented for eachVOBU. Also for each of the video pack, audio pack and sub-picture pack,the tag is written in the top four bytes of the pack header 5.

Since the same tag is added to the pack separated from the same VOBU,dependency relationship between the navy pack and the other video pack,audio pack and sub-picture pack is maintained upon decoding. Thereby, ina data decoding device according to the present invention, it ispossible to carry out decoding operation while observing the navy packand the video pack, audio pack and sub-picture pack depending from thenavy pack based on the tags. Hereafter, the value of the tag is referredto as a tag number.

FIG. 9 shows a configuration diagram of one embodiment of a datadecoding device for decoding VOB according to one embodiment of thepresent invention. The data decoding device generally includes ahardware 100 and a software 200. First, description is made for thehardware 100.

The hardware 100 includes a track buffer 101, a demux 102, a videobuffer 103, an audio buffer 104, a sub-picture buffer 105, a navy buffer105, a video decoder 107, an audio decoder 108, a sub-picture decoder109, a host interface part 110 and registers 111.

The VOB read out from a DVD disk 10 is stored in the track buffer 101 ofthe hardware 100. At this time, the VOB is managed for each VOBU unitwith a separation therebetween. Subsequent to the track buffer 101, thedemux 102 for separating the VOBU into respective packs of theabove-mentioned four types, i.e., the navy pack, video pack, audio packand sub-picture pack is connected.

Subsequent to the demux 102, the video buffer 103, the audio buffer 104,the sub-picture buffer 105 and the navy buffer 106 storing therespective packs are connected. Subsequent to the video buffer 103, theaudio buffer 104 and the sub-picture buffer 105, the registers 111storing the tags are connected respectively.

Specifically, the tag extracted from the video pack is stored in theregister (V_tag) 111 provided subsequent to the video buffer 103.Similarly, the tag extracted from the audio pack is stored in theregister (A_tag) 111 provided subsequent to the audio buffer 104. Thetag extracted from the sub-picture pack is stored in the register(Sp_tag) 111 provided subsequent to the sub-picture buffer 105.

Bit streams read out from the video buffer 103, the audio buffer 104 andthe sub-picture buffer 105 are decompressed by the video decoder 107,the audio decoder 108 and the sub-picture decoder 109, respectively,thus come to have a reproduced form of video, audio and subtitle, andare output from the hardware 100.

Next, description is made for the software 200. The software 200includes an STC 201, a current managing part 202, a navy spool 203, areproduction engine 204, an HLI control part 205 and an STC alarmregistration managing part 206.

The current manager 202 reads out the navy pack from the navy buffer106, and stores it in the navy spool 203. The reproduction engine 204reads the navy pack from the navy spool 203, and carries out control foractual data reproduction. In the reproduction engine 204, a pointer(Nv_tag) 207 for storing the tag extracted from the navy pack isprovided.

The reproduction engine 204 extracts the PCI from the navy pack thusread out from the navy spool 203, and transmits VOBU_E_PTM included inthe PCI to the STC alarm registration managing part 206. Thereproduction engine 204 transmits highlight information to the STC alarmregistration managing part 206 via the HLI control part 205.

VOBU_S_PTM included in the PCI is transmitted to the STC alarmregistration managing part 206 from the current managing part 202.VOBU_E PTM included in the PCI is transmitted to the STC alarmregistration managing part 206 from the reproduction engine 204.HL_S_PTM, HL_E_PTM and BTN_SL_E_PTM included in the HLI are transmittedto the STC alarm registration managing part 206 from the reproductionengine 204 via the HLI control part 205.

The STC alarm registration managing part 206 registers the receiveddata, i.e., time information included in the PCI, that is, VOBU_S_PTM,VOBU_E_PTM, HL_S_PTM, HL_E_PTM and BTN_SL_PTM in the STC 201 in theascending order. The STC 201 starts time measurement simultaneously upona start of data reduction, and, when a registered time has been reached,it notifies the reproduction engine 204 and the HLI control part 205 ofan alarm.

The reproduction engine 204 can observe the registers 111 connectedsubsequent to the video buffer 103, the audio buffer 104 and thesub-picture buffer 105 via the host interface part 110.

The data decoding device shown in FIG. 9 is one different from the datadecoding device shown in FIG. 2 in that a system for processing the tagsdescribed above is added. For detail, the data decoding device of FIG. 9is different from the data decoding device of FIG. 2 in that the datadecoding device of FIG. 9 additionally has tag adders 112 provided inthe demux 102, the registers 111 provided subsequent to the video buffer103, the audio buffer 104 and the sub-picture buffer 105, the pointer207 provided in the reproduction engine 204, and a system by which thereproduction engine 204 can observe the registers 111 via the hostinterface 110.

FIGS. 10 and 11 are a flow chart showing one example of operation of theabove-described data decoding device according to the embodiment of thepresent invention. Here, description is made paying attention to therespective buffers and the navy pack. In Step S31, it is determinedwhether or not the track buffer 101 still has a free storage space.

When a free storage space exists (Yes in Step S31), a VBO request isissued in Step S32, and, in Step S33, VOB is transferred from the DVDdisk 10 to the track buffer 101. After the processing of Step S33, StepS31 is returned to again. On the other hand, when there is no freerstorage space in the track buffer 101 (No in Step S31), Step S34 isexecuted, in which issuance of the VOB request is stopped.

Then in Step S35, VOB thus stored in the track buffer 101 is input tothe demux 102 for each unit of VOBU. VOBU thus input is separated intothe above-mentioned respective four types of packs in the demux 102, andhas the tags added thereto respectively as mentioned above by the tagadders 112. The demux 102 sends the packs thus having the tags addedthereto respectively to the respective buffers, i.e., the video buffer103, the audio buffer 104, the sub-picture buffer 104 and the navybuffer 106, which store the respective packs accordingly.

In Step S36, it is determined whether or not any one of the video buffer103, the audio buffer 104, the sub-picture buffer 105 and the navybuffer 106 has no more free storage space. When all of theabove-mentioned four buffers still have respective free storage spaces(No in Step S36), Step S35 is returned to, in which VOBU is again inputto the demux 102 from the track buffer 101. On the other hand, when anyone of these four buffers has no more free storage space (Yes in StepS36), Step S37 is carried out in which input of VOBU to the demux 102 isstopped. That is, when any one of the four buffers has no more freestorage space, input of VOBU to the demux 120 is stopped also withrespect to the other buffers still having free storage spaces.

Then, in Step S38, it is determined whether or not the navy pack isstored in the navy buffer 106. When no navy pack is stored yet in thenavy buffer 106 (No in Step S38), the processing of Step S38 isrepeated. On the other hand, when the navy pack is already stored in thenavy buffer 106 (Yes in Step S38), the current managing part 202 isnotified of a navy pack writing finish notification. Then in Step S39,the current managing part 202 obtains the navy pack from the navy buffer106 via the host interface part 110.

Then, in Step S40, the current managing part 202 stores, in the navyspool 203, the navy pack thus obtained from the navy buffer 106. In StepS41, it is determined whether or not the navy spool 203 comes to have nomore free storage space. When the navy spool 203 still has a freestorage space (No in Step S41), the current managing part 202 repeatsthe processing of Steps S38 through S41, and sends the navy pack,obtained from the navy buffer 106, to the navy spool 203, which thusstores it.

When the navy spool 203 comes to have no more free storage space (Yes inStep S41), the current managing part 202 executes Step S42, and thus,registers VOBU_S_PTM(0) in the STC alarm registration managing part 206in prior to other parameters. Then in Step S43, the reproduction engine204 obtains the first navy pack Nv_pck(0) from the navy spool 203.

In Step S44, the reproduction engine 204 extracts the tag from the navypack NV_pck(0), and stored it in the pointer 207. Then in Step S45, thereproduction engine 204 extracts HLI from the navy pack Nv_pck(0), andtransmits it to the HLI control part 205. In Step S46, the reproductionengine 204 registers VOBU_E_PTM(0) in the STC alarm registrationmanaging part 206.

In Step S47, the HLI control part 205 registers HL_S_PTM(0), HL_E_PTM(0)and BTN_SL_E_PTM(0) in the STC alarm registration managing part 206.

Then, in Step S48, the tag is extracted from the top video pack V_pck(0)stored in the video buffer 103, and is then stored in the register(V_tag) 111. Similarly, in Step S49, the tag is extracted from the topaudio pack A_pck(0) stored in the audio buffer 104, and is then storedin the register (A_tag) 111. In Step S50, the tag is extracted from thetop video pack Sp_pck(0) stored in the sub-picture buffer 105, and isthen stored in the register (Sp_tag) 111. At this time, all the tagnumbers stored in the register (V_tag) 111, the register (A_tag) 111 andthe register (Sp_tag) 111 have the value of ‘1’.

In the processing so far, reproduction preparation for the first navypack Nv_pck(0) is completed. The processing of Steps S42 through S50 iscalled ‘reproduction standby’. In Step S51, it is determined whether ornot reproduction is started therefor. Processing of Step S51 is repeatedunless it is determined that reproduction is to be started (No in StepS51). On the other hand, when it is determined that reproduction is tobe started (Yes in Step S51), decoding of the bit streams stored in thevideo buffer 103, the audio buffer 104 and the sub-picture buffer 105 isstarted. In Step S53, the STC 201 starts counting.

Then in Step S54, the current managing part 202 registers VOBU_S_PTM(1)in the STC alarm registration managing part 206. In Step S55, it isdetermined whether or not a reproduction start time VOBU_S_PTM(1) forthe second navy pack Nv_pck(1) is reached.

When it is determined that the reproduction start time VOBU_S_PTM(1) isnot yet reached (No in Step S55), the processing of Step S55 isrepeated. On the other hand, when it is determined that the reproductionstart time VOBU_S_PTM(1) for the second navy pack Nv_pck(1) has beenreached (Yes in Step S55), the STC 201 executes Step S56, and thus, itnotifies the reproduction engine 204 and the HLI control part 205 of analarm. In Step S57, the reproduction engine 204 obtains the second navypack Nv_pck(1) from the navy spool 203.

In Step S58, the reproduction engine 204 extracts the tag from thesecond navy pack Nv_pck(1), and stores in the pointer 207. That is, thetag stored in the pointer is updated.

In Step S59, the reproduction engine 204 extracts HLI from the secondnavy pack Nv_pck(1) and transmits it to the HLI control part 205. InStep S60, the reproduction engine 204 registers VOBU_E_PTM(1) in the STCalarm registering managing part 206.

In Step S61, the HLI control part 205 registers HL_S_PTM(1), HL_E_PTM(1)and BTN_SL_E_PTM(1) in the STC alarm registration managing part 206.

In the register (V_tag) 111, the tag extracted from the video packV_pck(1) stored in the video buffer 103 is stored. Similarly, in theregister (A_tag) 111, the tag extracted from the audio pack A_pck(1)stored in the audio buffer 104 is stored. In the register (Sp_tag) 111,the tag extracted from the sub-picture pack Sp_pck(1) stored in thesub-picture buffer 105 is stored.

In Step S62, it is determined whether or not reproduction is continued.When it is determined that reproduction is continued (Yes in Step S62),the processing of Steps S54 through S62 is carried out for the furthersubsequent navy pack. That is, as a result of the processing of StepsS54 through S62 being repeated, data reproduction from the DVD disk iscarried out.

On the other hand, when it is determined that reproduction is no morecontinued (No in Step S62), decoding of the bit streams stored in thevideo buffer 103, the audio buffer 104 and the sub-picture buffer 105 isstopped. Then in Step S64, the STC 201 stops counting, and holds thecurrent count value.

That is, in the flow chart of FIGS. 10 and 11, every time when thereproduction engine 204 obtains the navy pack Nv_pck(n+1) from the navyspool 203, the tag stored in the pointer 207 is updated. Similarly, inthe register (V_tag) 111, the tag extracted from the video packV_pck(n+1) stored in the video buffer 103 is then stored. In theregister (A_tag) 111, the tag extracted from the audio pack A_pck(n+1)stored in the audio buffer 104 is then stored. In the register (Sp_tag)111, the tag extracted from the sub-picture pack Sp_pck(n+1) stored inthe sub-picture buffer 105 is then stored.

Accordingly, when decoding is carried out normally, the tag numberstored in the pointer 207 and the tag number stored in the register(V_tag) 111, the register (A_tag) 111 and the register (Sp_tag) 111agree with each other.

Next, a state transition of the four buffers, i.e., the video buffer103, the audio buffer 104, the sub-picture buffer 105 and the navybuffer 105, the navy spool 203, the register 111 and the pointer 207occurring when VOBU such as that shown in FIG. 5 is reproduced by thedata decoding device according to the embodiment of the presentinvention and voice switching is carried out from English to Japanese,is described with reference to FIGS. 12 and 13.

A state of FIG. 12, (A) is an initial state before a start ofreproduction. In this state, the four buffers and the navy spool 203 arefree as shown. The track buffer not shown in FIGS. 12 and 13 is alsofree.

Since the track buffer 101 is free in this state of FIG. 12, (A), a VOBrequest is issued, and transfer of VOB from the DVD disk 10 to the trackbuffer 101 is started. After that, VOB thus stored in the track buffer101 is input to the demux 102 for each VOB unit, is separated into therespective four types of packs described above by the demux 102, whichare than stored in the respective buffers, after the above-mentionedtags are added thereto respectively. After that, the navy buffer 106comes to have no more free storage space, input of VOBU to the demux 102is stopped, and issuance of the VOB request is stopped.

A state of FIG. 12, (B) is a state of the above-mentioned reproductionstandby. In this state, the reproduction engine 204 obtains the top navypack Nv_pck(0) from the navy spool 203, extracts the tag from the navypack Nv_pck(0), and stores the tag in the pointer 207. At this time, thetag number stored in the pointer 207 is “1”.

Similarly, the tags are extracted from the top video pack V_pck(0) andthe top audio pack A_pck(0) stored in the video buffer 103 and the audiobuffer 104, respectively, and are stored in the registers (V_tag) 111and the register (A_tag) 111, respectively. At this time, the tagnumbers stored in the register (V_tag) 111 and the register (A_tag) 111are also “1”.

Since no sub-picture pack is multiplexed in VOBU of FIG. 5, nosub-picture pack is stored in the sub-picture buffer 105. Therefore, thetag number stored in the register (Sp_tag) 111 is kept unchanged asbeing “0”.

In a state of FIG. 12, (C), reproduction is started, the reproductionengine 204 reads out the navy packs from the navy spool 203 and consumesthem. In the state of FIG. 12, (C), the reproduction engine 204 obtainsthe top navy pack Nv_pck(1) from the navy spool 204, extracts the tagfrom the navy pack Nv_pck(1), and stores the tag in the pointer 207. Atthis time, the tag number stored in the pointer 207 thus becomes “2”.

Similarly, the video packs and the audio packs stored in the videobuffer 103 and the audio buffer 104 respectively are decompressed by thevideo decoder 107 and the audio decoder 108, respectively, thus become aform of video and audio, respectively, are output from the hardware 100,and thus, are consumed. In the state of FIG. 12, (C), the tags areextracted from the subsequent video pack V_pck(1) and audio packA_pck(1) stored in the video buffer 103 and the audio buffer 104, andare stored in the register (V_tag) 111 and the register (A_tag) 111,respectively. At this time, each of the tag numbers stored in theregister (V_tag) 111 and the register (A_tag) 111 also becomes “2” asshown. It is note that the tag numbers of the register (V_tag), theregister (A_tag), the register (Sp_tag) and the pointer are indicated asV_tag, A_tag, Sp_tag and Nv_tag in FIGS. 12 and 13).

In the state of FIG. 12, (C), the audio packs A_pck(E) corresponding toEnglish voice are stored in the audio buffer 104, and thus, an Englishvoice is output. In FIGS. 12 and 13, the navy packs consumed are crossedoff by canceling lines (-).

Then, it is assumed that a user issues an instruction to switch thevoice language. Upon issuance of this voice switching instruction, thedata decoding device flashes (deletes) the audio packs A_pck(E)currently stored in the audio buffer 104. After that, the register(A_tag) 111 is rewritten by a special value ‘FFFFFFFF’ (all 1's) whichmeans that the system itself has flashed all the packs stored in thebuffer for a certain reason.

A state of FIG. 12, (D) is a state in which, the voice switchinginstruction has been issued, the audio packs have been flashed from theaudio buffer 104, and the register (A_tag) 111 has been rewritten into‘FFFFFFFF’. The video packs stored in the video buffer 103 have beenconsumed, and thus, the video buffer 103 has become free. As a result,the register (V_tag) 111 has a special value ‘0’ indicating that no packexists, as shown.

The reproduction engine 204 observes the tag numbers stored in theregister (V_tag) 111, the register (A_tag) 111 and the pointer 207 eachtime of updating the pointer 207. When the tag numbers stored in theregister (V_tag) 111, the register (A_tag) 111 and the pointer 207 donot agree with each other, the reproduction engine 204 further obtainsthe occupied amounts in the video buffer 103, the audio buffer 104 andthe sub-picture buffer 105.

Then, according to the flow chart of FIG. 14, the reproduction engine204 determines whether or not the navy packs stored in the navy buffer106 should be flashed. FIG. 14 shows a flow chart of one example of navybuffer flashing processing.

In Step S100, it is determined whether or not the reproduction starttime VOBU_S_PTM(n+1) of the (n+2)-th navy pack Nv_pck(n+1) is reached.When it is determined that the reproduction start time VOBU_S_PTM(n+1)has not been reached (No in Step S100), the processing of Step S100 isrepeated.

When it is determined that the reproduction start time VOBU_S_PTM(n+1)has been reached (Yes in Step S100), the STC 201 executes Step S101, andnotifies the reproduction engine 204 and the HLI control part 205 of analarm. Then in Step S102, the reproduction engine 204 obtains the navypack Nv_pck(n+1) from the navy spool 203. Then, in Step S103, thereproduction engine 204 extracts the tag from the navy pack Nv_pck(n+1),and stores the tag in the pointer 207. That is, the tag stored in thepointer 207 is updated.

Then, in Step S104, the reproduction engine 204 obtains the tag numbersfrom the register (V_tag) 111, the register (A_tag) 111 and the register(Sp_tag) 111. Then, in Step S105, the reproduction engine 204 determineswhether or not all the tag numbers obtained from the register (V_tag)111, the register (A_tag) 111, the register (Sp_tag) 111 and the pointer207 agree with each other.

When all the tag numbers agree with each other (Yes in Step S105), thereproduction engine 204 determines that the state is normal, andfinishes the processing of the flow chart shown in FIG. 14. On the otherhand, when all the tag numbers do not agree with each other (No in StepS105), the reproduction engine executes Step S106. Then, in Step S106,the reproduction engine 204 determines whether or not any one of the tagnumbers obtained from the register (V_tag) 111, the register (A_tag) 111and the register (Sp_tag) 111 is all 1's.

When it is determined that none of the tag numbers is all 1's (No inStep S106), the reproduction engine 204 determines not to flash the navybuffer 105, and finishes the processing of the flow chart of FIG. 14. Inthis case, in consideration of a possibility that reading of the navypack has been failed in, the navy buffer 106 is not flashed for thepurpose of using the immediately preceding navy pack for a substitution.When it is determined that any of the tag numbers is all 1's (Yes inStep S106), the reproduction engine 204 executes Step S107.

In Step S107. the reproduction engine 204 obtains the occupied amount ofeach of only some of the video buffer 103, the audio buffer 104 and thesub-picture buffer 105 for each of which the register (V_tag) 111, theregister (A_tag) 111 or the register (Sp_tag) 111 does not have the tagnumber of all 1's. Then in Step S108, the reproduction engine 204determines whether or not each occupied amount obtained in Step S107 is0. When any occupied amount obtained is not 0 (No in Step S108), thereproduction engine 204 determines not to flash the navy buffer 106, andfinishes the processing of the flow chart of FIG. 14.

In this case, any one of the video buffer 103, the audio buffer 104 andthe sub-picture buffer 105 has been flashed for some reason. However,the packs to be reproduced still remain in the buffers which have notbeen flashed. Accordingly, the navy buffer 106 is not flashed. When eachoccupied amount is 0 (Yes in Step S108), the reproduction engine 204executes Step S109, flashes (i.e., deletes all the packs from) the navybuffer 106, and finishes the processing of the flow chart of FIG. 14.

In a state of FIG. 13, (E), the navy buffer 106 is flashed, and thus,becomes free. When the navy buffer 106 thus becomes free, immediatelynew VOBU is input to the demux 102, and, as shown in FIG. 13, (F), theaudio pack A_pk(J) is given the audio buffer 104. After that, as shownin FIG. 13, (G), storage of the audio pack(J) in the audio buffer 104 iswaited for, and, after it is stored, reproduction is started.

The value of the tag added to each pack of the four types and the valueof the tag stored in the registers 111 and the pointer 207 are changedas shown in FIG. 15. FIG. 15 shows the value of the tag added to eachpack of the four types and the value of the tag stored in the registersand the pointer.

In the data decoding device shows in FIG. 2, as mentioned above, a timefor actually consuming the navy packs is required for voice switching.On the other hand, according to the data decoding device in theembodiment of the present invention, maximum 0.5 seconds is requireafter the audio buffer 104 is flashed, that is, only a time forconsuming one navy pack is required. Accordingly, in the data decodingdevice according to the present invention, merely a thus-shortened voiceinterruption occurs upon voice switching, and the user hardly recognizesvoice interruption upon voice switching.

That is, when the video buffer 103, the audio buffer 104 and thesub-picture buffer 105 have no video pack, no audio pack and nosub-picture pack to be controlled, the navy buffer 106 is flashed. As aresult, it is possible to shorten the voice interruption upon voiceswitching.

According to the present invention, dependency relationship between thenavy pack and the video pack, the audio pack and the sub-picture pack ismaintained upon decoding. Thereby, it is possible to determine whetheror not there should occur a problem if the navy packs are deleted. Then,based on this determination result, it is possible to delete the navypacks appropriately if necessary.

The track buffer 101 and the demux 102 act as an inverse multiplexingpart; and the other part of the hardware 100 than the track buffer 101and the demux 102 as well as the software 200 act as a decoding part,for example.

Further, the present invention is not limited to the above-describedembodiment, and variations and modifications may be made withoutdeparting from the basic concept of the present invention claimed below.

The present application is based on Japanese Priority Application No.2004-270071 filed on Sep. 16, 2004, the entire contents of which arehereby incorporated herein by reference.

1. A data decoding device for decoding compressed and coded data,comprising: an inverse multiplexing part configured to separatecompressed and coded data into a plurality of unit data, then separate,from the unit data, more than one type of a data pack, and add a tagthereto such that the data pack can be identified as originating fromthe same unit data; and a decoding part configured to monitor the tag,while carrying out decoding of the data pack separated from the sameunit data, for each unit of the unit data.
 2. The data decoding deviceas claimed in claim 1, wherein: after further separating the more thanone type of data pack from the unit data, said inverse multiplexing partadds the tag to a pack header configuring a part of the data pack. 3.The data decoding device as claimed in claim 1, wherein: said inversemultiplexing part adds, as the tag, a value incremented by one for eachdata pack.
 4. The data decoding device as claimed in claim 1, wherein:after adding the tag to the data pack, said inverse multiplexing partstores the data pack in a buffer determined according to the type of thedata pack.
 5. The data decoding device as claimed in claim 4, wherein:said inverse multiplexing part separates a video object (VOB) accordingto a DVD standard into a plurality of video object units (VOBU), and,from the video object unit, further separates a navy pack, a video pack,an audio pack, and a sub-picture pack, and adds the tags thereto suchthat the navy pack, the video pack, the audio pack and the sub-picturepack may be identified as originating from the same VOBU.
 6. The datadecoding device as claimed in claim 5, wherein: when reading the navypack from the buffer determined according to the type of the navy pack,said decoding part separates the tag added to the navy pack therefromand stores it in a pointer, while, when reading the video pack, audiopack and sub-picture pack from the respective buffers determinedaccording to the respective types of the video pack, audio pack andsub-picture pack, said decoding part separates the tags added to thevideo pack, audio pack and sub-picture pack therefrom and stores them inregisters.
 7. The data decoding device as claimed in claim 6, wherein:said decoding part observes the tags stored in the pointer periodically,and, based on agreement or disagreement in the tags stored of thepointer and the registers, determines whether or not the navy packshould be deleted from the buffer determined according to the type ofthe navy pack.
 8. The decoding device as claimed in claim 7, wherein:said decoding part deletes all the audio packs or the sub-picture packsfrom the buffer determined according to the type of the audio pack orthe sub-picture pack, as a procedure of audio switching or subtitleswitching, and rewrites the tag added to the audio packs or thesub-picture packs and stored in the register into a predetermined value.9. The data decoding device as claimed in claim 8, wherein: saiddecoding part deletes the navy packs stored in the buffer when the tagsstored in the pointer and the registers do not agree with each other,the tag added to the audio pack or the sub-picture pack has beenrewritten into a predetermined value, and also, a capacity of each ofsome of the buffers determined according to the types of the video pack,the audio pack and the sub-picture pack, for each of which the tag hasnot been rewritten into the predetermined value, is free.
 10. The datadecoding device as claimed in claim 1, wherein: said navy pack includesreproduction control information for the video pack, audio pack andsub-picture pack.
 11. A data decoding method for decoding compressed andcoded data, comprising the steps of: a) separating compressed and codeddata into a plurality of units of unit data; b) further separating, fromthe unit data, more than one type of a data pack; c) adding a tagthereto such that the data pack can be identified as originating fromthe same unit data; and b) monitoring the tag, while carrying outdecoding of the data pack originating from the same unit data, for eachunit of the unit data.
 12. A semiconductor integrated circuit configuredto decode compressed and coded data, comprising: an inverse multiplexingpart configured to separate compressed and coded data into a pluralityof units of unit data, then separate, from the unit data, more than onetype of a data pack, and adding thereto a tag such that the data packcan be identified as originating from the same unit data; and a decodingpart configured to monitor the tag, while carrying out decoding of thedata pack originating from the same unit data, for each unit of the unitdata.
 13. A data decoding system for decoding compressed and coded data,comprising: an inverse multiplexing part configured to separatecompressed and coded data into a plurality of units of unit data, thenseparate, from the unit data, more than one type of a data pack, andadding thereto a tag such that the data pack can be identified asoriginating from the same unit data; and a decoding part configured tomonitor the tag, while carrying out decoding of the data packoriginating from the same unit data, for each unit of the unit data.